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1. Background Information

Do Son Water treatment plant (DSWTP) is located in Van Son ward, Do Son district, Hai Phong city

with total area of 12.67 km2. As the WTP is located far away from the river water resources, it

receives the raw water through upstream pumping station (He river intake pumping station). It runs

under the management and operation of Hai Phong Water Supply Company, Ltd. DSWTP was

constructed in 1959-1961 with a capacity of 1,000 m3/d which was then expanded to the treatment

capacity to 5,000 m3/d in 1987 and 7000 m3/day in 2013. This plant supplies treated water for the

entire Do Son district, several areas along to 353 street of Duong Kinh district and Kien Thuy district.

The raw water is treated in two stages. Firstly, it is treated in the He river intake pumping station and

is then treated in the DSWTP. Further background information about Do Son water treatment plant

is presented in Table 1.

Table 1 Overall Information of Do Son Water Treatment Plant

Constructed Year 1959 - 1961

Water Source He River

Number of connections (by 3/2013) 9,092

For Households 8,804 (96.8%)

For Administrations 93 (1 %)

For Manufactures 53 (0.6%)

Capacity (m3/day) 7000

Automation No

Topography Plain/Tropical

Date of access of the source information 5 September, 2015

References Water Safety Plan (2013) Hai Phong Water Supply Company

2. Water treatment Process 2.1 He river water supply station

The major process as follows: Raw water intake (Bamboo Screen, bar screen) → Pre-Chlorination → Coagulation (Al2(SO4)3)→ Flocculation → Sedimentation → Filtration (Silica sand/Silica sand + Anthracite carbon) → Chlorination Disinfection (Dose: 0.5 – 0.8 mg/L) → Pumping station.

Do Son Water Treatment Plant

Hai Phong, Vietnam

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Figure 1 Schematic Diagram of He water Intake Pumping Station

2.1.1 Chemical feeding and mixing Alum sulfate is mainly used for water treatment as a coagulant and liquid chlorine for pre- and post-

chlorination.

There are two mixing tanks (each with the volume of 1.5 m3) and one solution tank. The mean

solution concentration is around 5%. Mixing machine with the capacity of 1.5 KW and 75 rpm is used.

2.1.2. Sedimentation Sedimentation basin has a surface area of 1,000 m2 and volume of 3,000 m3. The water level of this

tank is in the range of 1.6–3.0 m. Retention time of sedimentation basin is 4 hours at the production

capacity of 350 m3/h.

2.1.3. Filtration There are two rapid filtration tanks in DSWTP. The first rapid sand filter was constructed in 2007 and

it has 8 sub-tanks, each with a surface area of 1.82 m2. The second filtration tank was constructed in

2011 and it consists of 10 sub-tank, each with the surface area of 1.89 m2. The operational capacity

of both the rapid sand filter is 300 m3/h.

The media used in filters is fine sand with filter depth of 70 cm. The filtration rate is maintained in

the range of 8 -15 m/h. This filtration tank is semi-automatic and it has a backwash cycle of 8-12 h.

The turbidity of the filtrate is less than or equal to 3 NTU.

2.1.4 Disinfection Liquid chlorine is utilized for pre and post-disinfection. Chlorine dose is determined based on Jar test

performed in the technical quality room. To test the free chlorine in water, DPD (Poly-(1, 4) D-

glucosamine) tablet test or orthotolidine test is employed.

It consists of two functional chlorinator and a reserve chlorinator. Among the two functional

chlorinator, one with the capacity of 5 kg/hr is used for the pre-chlorination while the other one with

the capacity of 2.5 kg/hr is used for disinfection

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2.1.5 Pumping station

There are two horizontal centrifugal pumps with the following specifications:

Capacity =350 m3/h Total Head= 60 m Power motor= 75 KW I= 132 A 2.2 Do Son Water Treatment Plant The treatment processes in DSWTP are as follow: Water source from He river intake pumping station → Raw water reservoir → 1st pumping station → Rapid sand filtration → Disinfection → Pure water storage tank → 2nd pumping station → Distribution system

Figure 2 Schematic Diagram of Don Son Water Treatment Plant

2.2.1 Raw water reservoir

This reservoir consists of an area of 2,800 m2 and has a volume of 8,000 m3 (Figure 3). The water level is in range of 1.0 – 2.8 m and has a retention time is 20 hours in the case of operation capacity of 250 m3/h.

Figure 3 Do Son raw water reservoir

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2.2.2 The first pumping station There are 5 operational pumps in the first pumping station which can pump water with the

maximum capacity of 345 m3/h (Figure 4). The details are shown in the Table 2.

Table 2 Specifications of pumps used in the first pumping station

Pump Type - Model Capacity (m3/h) Total head (m) Power Motor

(KW) I (A)

1 8BA-18 285 18 22 40

2 100E-80A 176.4 28 22 41.8

3 100E-80A 176.4 28 22 41.8

4 Д1000-15 (wash) 1,000 13 76 137

5 N5 (air) 25.2 m3/min -- 28 52

Figure 4 Do Son raw water reservoir

2.2.3 Filtration

DSWTP utilizes anthracite carbon (0.5 m) and silica sand (0.7 m) as filter media and has a filtration

rate of 8-10 m/h. DSWTP has a circular filtration tank with the surface area of 28 m2 and a

rectangular filtration tank consisting of three segment, each with an area of 3.4 m2.

(a) Circular filtration tank (b) Vertical filtration tank

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2.2.4 Disinfection process

The liquid chlorine (Figure 6) is used for the disinfection and the quantity to be used is determined from the Jar test performed in the technical quality room. The residual (free) chlorine in treated water is tested by DPD tablets or Orthotolidin solution. There are two chlorinators with the capacity of 2 kg/hr.

Figure 6 Filtration tanks 2.2.5 Treated water storage tank

DSWTP consist of a clean water storage tank with a volume of 1,000 m3. The liquid chlorine is injected into water pipeline which conveys water to the storage tank. It has a retention time of 30 min.

Figure 7 Pure water storage tanks 2.2.6 The second pumping station There are 7 pumps (5 horizontal centrifugal pumps and 2 vertical centrifugal pumps) with the combined capacity is 360 m3/h and pressure of 3-4.5 bar (Figure 8). Specifications of these pumps are illustrated in Table 3.

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Table 3 Specifications of pumps used in the second pumping station

Pump Type - Model Capacity (m3/h) Total head (m) Power Motor

(KW) I (A)

1 125PJMO-200 150 - 180 45 30 56

2 125PJMO-200 150 - 180 45 30 56

3 4BA-64 105 69.5 40 74

4 4BA-64 105 69.5 40 74

5 YHC 180 180 45 30 56

6 CR32 30 29.6 4 8.95

7 CR32 30 29.6 4 8.95

Figure 8 Pumps used in the second pumping station

2.2.7 Distribution system Distribution system has a high leakage ratio of 21% as recorded in 2012. The treated water is supplied to consumers via water supply network which consists of following pipelines: Table 4: Distribution of Pipeline

SN Diameter Total Length (Km)

1 D300 9.47

2 D150-D290 15

3 D32-D100 35

4 D25 27

Distribution system consists of two horizontal centrifugal pumps (specification in Table 5) and two storage tanks (800 m3 and 1,000 m3). Table 5 Specifications of pumps used in distribution system

Pump Type - Model Capacity (m3/h) Total head (m) Power Motor

(KW) I (A)

1 Д320-50T 160 50 22 50

2 125PJMO-200 135 20 15 32

3. Aspects of treatment processes posing most difficulty for daily operation The raw water is often contaminated by organic pollutants from domestic wastewater and fertilizers which causes increased dosage of coagulants and disinfectant resulting in the rise of treatment cost.

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4. Aspects of water services management in general posing most difficulty at the moment

Raw water from He river is contaminated from pollution sources as: - Industrial wastewater along 355 street, Duong Kinh district which is discharged to Tieu Tra and

Hoa Binh canals. - Sewage, domestic solid wastes and water leakage from septic tanks of households living along

with these canals. - Pollutants from agriculture activities as pesticides, herbicides, fertilizers, livestock wastes. - High percentage of non-revenue water

5. Measures taken now to cope with 3) and 4)

Hai Phong Water Supply Company has implemented the water safety plan (WSP) following the manual of WHO since 2011. The main objectives of WSP are indicated as follows: - Ensuring: maintenance of water pressure, stable supply of water in sufficient quantity and

meeting required water quality standards. - Planning to cope with unexpected incidents and hazards which may occur during the entire

production process (water intake to distribution). - Contributing to protect public health, reducing water-related disease and disease prevention - Contributing to reduce wastage, saving water resources and environmental protection Some activities carried out to protect the raw water sources are: - Compliance monitoring of the industries to prevent illegal discharge of waste and wastewater in

the water source - Conducting public awareness programs to raise the residential awareness level.

6. Recent investment made for the plant’s improvement

There has not been any recent investment for the improvement of DSWTP but the company has

plans to modify the He river intake pumping station to high pressure pumping station and construct

a new WTP for Do Son area in next five year. The company has also planned to replace the

distribution system to minimize the leakage ratio in next five year.

7. Technologies, facilities or other types of assistance needed to better cope with operational and management difficulties in 3) and 4).

- Online monitoring system should be installed for better control and operation - Since surface runoff from the farmland pollutes the raw water leading to high operational

cost of treatment, efforts to reduce the inorganic pollutants at different level is needed as a part of social campaign.

8. Customer’s opinion on water quality and water services in general

DSWTP majorly receives the complaint regarding the odor in the treated water through telephone,

which is acted as soon as possible by the operator. In case of any unresolved or unacted complaints,

complainer can further register their complaints to the Customer Relation Office in Hai Phong Water

Supply Company.

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9. Advanced technology used in this water treatment plant (if any) or any points to improve the

process, water quality and capacity.

Online monitoring system is needed for the real time monitoring of the water quality at different

level to increase the efficiency of the operators.

10. Other highlights

In 2012, the percentage of non-revenue water was 21.0%.

11. Water quality data

All the measured parameter were below the Vietnam standard for drinking water.

Table 6 Water quality data for the year 2014

No Parameters Unit

Raw water of He River

Do Son treated water

QCVN 01:2009/BYT

- Standard

Min Max Min Max

1 Color <5 <5 ≤ 15

3 Turbidity NTU 12.84 16.72 0.18 0.31 ≤ 2

4 pH 7.23 7.52 7.04 7.36 6.5-8.5

5 Total Ca and Mg

mgCaCO3/L 90 156 93 152 ≤ 300

6 Cl- mg/L 35.94 92.21 45.80 87.86 ≤ 250

7 Permanganate mgO2/L 3.06 6.03 0.85 1.78 ≤ 2,0

8 Mn mg/L 0.087 0.596 0.007 0.028 ≤ 0.3

9 Nitrate/N mg/L 0.442 1.266 0.480 1.335 ≤ 11.36

10 Nitrite/N mg/L 0.010 0.116 <0,002 0.013 ≤ 0.91

11 Total Fe mg/L 0.104 0.857 <0,02 0.050 ≤ 0.30

12 Sulfate mg/L NA NA 22.00 54.18 ≤ 250

13 Residual chlorine

mg/L NA NA 0.53 0.73 0.3-0.5

14 Total Coliform MPN/100mL 2956 8422 0 0 0

15 Fecal Coliform MPN/100mL 2956 8422 0 0 0

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12. Other graphical information

Table 7: Yearly data of the treated water

Year No. of

samples

Turbidity

(NTU)

Salinity

(mg Cl/L)

Permanganate

(mgO2/L)

Free

Chlorination

Total

Coliform

Fecal

Coliform

2010 816 0.32 53.41 1.36 0.7 0 0

2011 806 0.28 44.25 1.28 0.7 0 0

2012 807 0.24 47.56 1.24 0.7 0 0

QCVN:

01_2009/BYT ≤ 2 ≤ 250 ≤ 2 0.5 – 0.8 0 0

13. References

http://haiphong.gov.vn/Portal/Detail.aspx?Organization=DOANHNGHIEP&MenuID=4756&ContentID=12156

http://www.msbs.com.vn/Sites/QuoteVN/SiteRoot/1_201507cdab5._Ban_cong_bo_thong_tin_cap_

nuoc_HP.pdf

Water safety plan of Hai Phong water supply company, Ltd.

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Prepared by:

Mr. Cao Van Quy

Hai Phong Water Supply Company

No. 54, Dinh Tien Hoang Street, Hong Bang District, Hai Phong City

Email: caovanquyhp@gmail.com

Disclaimer:

This report was prepared for the NewTap project, which is funded by the Japan Water

Research Center. JWRC assumes no responsibility for the content of the report or for the

opinions or statements of fact expressed in it. This report is presented solely for

informational purposes. The copyright of this report is reserved by JWRC. For more details

about the copyright, please refer to the site policy of the NewTap website.

Date: August, 2015

URL: http://www.jwrc-net.or.jp/aswin/en/newtap

Email: newtap@jwrc-net.or.jp